CANCER BIOLOGY - The cell kinetics of cells from human skin in normal and disease states are being studied in vitro. Keratinocytes from hyperplastic epithelium have exhibited increased proliferative behavior in culture compared with normal keratinocytes. Human fibroblasts from the upper (papillary) and lower (reticular) dermis from the same biopsy specimen exhibit different proliferative behaviors in vitro. Rabbit keratinocytes are resistant to methotrexate in vitro. Lymphomatous tissue from mycosis fungoides (MF) could not be propagated in athymic nude mice. In patients with MF lymphocytic response to mitogenic stimulation becomes depressed in advanced stages of disease. Antibody-dependent cell-mediated cytotoxicity is normal in classical infiltrative MF and depressed in erythrodermic MF. CARCINOGENESIS - Mechlorethamine applied topically is an effective carcinogen in hairless mice. Mechlorethamine and retinoic acid greatly enhance the carcinogenic properties of simulated sunlight in hairless mice. CANCER THERAPY - A protocol using both total-skin electron beam radiation and topically-applied mechlorethamine has been developed for patients with MF. Several groups of nonsteroidal anti-inflammatory substances not heretofore recognized have been identified that eradicate the cellular infiltrate in lesions of MF.